x402 Preflight · blog

Field notes on x402

What a paid endpoint actually returns, what a buyer agent does with it, and what to fix. Everything here comes from live checks against published endpoints, not from theory.

Posts

• x402 Bazaar census: what 26,692 paid endpoints actually return — 18 October 2026 · 9 min read
  87.7% of the Bazaar charges correctly, 3.0% has a defensible defect, the median price is one cent, and a handful of domains hold most of the catalogue. Full numbers, method and caveats.
• What each HTTP status code means when your API sells over x402 — 18 October 2026 · 7 min read
  A 402 is the only response that lets an agent buy. What 200, 405, 400, 404, 401, 403, 410, 500 and 503 mean on a paid endpoint, what the buying agent sees, and what to fix.

Answers, by topic

The long-form answers published before this blog live in the guides: Guides & answers — payment configuration, discovery requirements, why an endpoint returns 200 without charging, why a listing never shows up in the Bazaar, and x402 versus card rails.

Back to x402 Preflight — check any endpoint read-only, without a wallet.